PCT Published Application WO 2013/155590 A2 published on 17 Oct. 2013 and incorporated herein by reference describes a device that includes a plurality of nanowires functionalized with different functionalizing compounds. The method includes functionalizing the nanowires with a functionalizing compound, dispersing the nanowires in a polar or semi-polar solvent, aligning the nanowires on a substrate such that longitudinal axes of the nanowires are oriented about perpendicular to a major surface of the substrate, and fixing the nanowires to the substrate.